DTC C1073: Malfunction of motor drive circuit: Diagnosis

Required Special Tools:

MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
MB991974: ABS check harness

STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use scan tool to diagnose the CAN bus lines.

Q: Is the check result normal?
1. YES: Go to Step 3.
2. NO: Repair the CAN bus lines (Refer to CAN BUS DIAGNOSTICS TABLE ). On completion, go to Step 2.
STEP 2. Check whether the DTC is reset.
Q: Is DTC C1073 set?
1. YES: Go to Step 3.
2. NO: The procedure is complete.
STEP 3. Battery check
Refer to BATTERY TEST .

Q: Is the battery in good condition?
1. YES: Go to Step 4.
2. NO: Charge or replace the battery.
STEP 4. Charging system check
Refer to GENERATOR OUTPUT LINE VOLTAGE DROP TEST .

Q: Is the charging system in good condition?
1. YES: Go to Step 5.
2. NO: Repair or replace the charging system component(s). Then go to Step 11.
STEP 5. Connector check: A-03 ABS-ECU connector
Q: Is the check result normal?
1. YES: Go to Step 6.
2. NO: Repair the defective connector. Then go to Step 11.
STEP 6. Fusible link check: Check fusible link No. 26.
Visually check for open circuit in the fusible link No. 26.

Q: Is the check result normal?
1. YES: Go to Step 8.
2. NO: Go to Step 7.
STEP 7. Resistance measurement at A-03 ABS-ECU connector
1. Disconnect the ABS-ECU connector, connect special tool ABS check harness (MB991974) to the harness-side connector, and then measure the resistance at the special tool connector side.
  NOTE: Do not connect the special tool to ABS-ECU.
2. Disconnect the fusible link No. 26.
3. Measure the resistance between the terminal No. 13 and the body ground.
  OK: No continuity
Q: Is the check result normal?
1. YES: Replace the fusible link No. 26. Then go to Step 11.
2. NO: The short circuit may be present in the power supply circuit. Repair the wiring harness between the A-03 ABS-ECU connector terminal No. 13 and the fusible link No. 26, and then replace the fusible link No. 26. Then go to Step 11.
  
  Fig 1: Measuring Resistance Between Terminal No. 13 And Body Ground
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 8. Voltage measurement at the A-03 ABS-ECU connector
1. Disconnect the ABS-ECU connector, connect special tool ABS check harness (MB991974) to the harness-side connector, and measure the voltage at the special tool connector side.
  NOTE: Do not connect the special tool to ABS-ECU.
2. Measure the voltage between terminal No. 13 and body ground.
  OK: Battery voltage
Q: Is the check result normal?
1. YES: Go to Step 9.
2. NO: The open circuit may be present in the power supply circuit. Repair the wiring harness between the A-03 ABS-ECU connector terminal No. 1 and the fusible link No. 26. Then go to Step 11.
  
  Fig 2: Measuring Voltage Between Terminal No. 13 And Body Ground
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 9. Resistance measurement at A-03 ABS-ECU connector
1. Disconnect the ABS-ECU connector, connect special tool ABS check harness (MB991974) to the harness-side connector, and then measure the resistance at the special tool connector side.
  NOTE: Do not connect the special tool to ABS-ECU.
2. Measure the resistance between terminal No. 1 and body ground, and between terminal No. 14 and body ground.
  OK: Continuity exists (2 Ω or less)
Q: Is the check result normal?
1. YES: Go to Step 10.
2. NO: An open circuit may be present in the ground circuit. Repair the wiring harness between the A-03 ABS-ECU connector terminal No. 1 and the body ground, and between the A-03 ABS-ECU connector terminal No. 14 and the body ground. Then go to Step 11.
  
  Fig 3: Measuring Resistance Between Terminal No. 1 And Body Ground
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 10. Check whether the DTC is reset.
1. Erase the DTC.
2. Drive the vehicle at 12 mph (20 km/h) or higher.
  NOTE: The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12 mph (20 km/h) or higher.
Q: Is DTC C1073 set?
1. YES: Replace the hydraulic unit (integrated with ABS-ECU) (Refer to HYDRAULIC UNIT ). Then go to Step 11.
2. NO: Intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).
STEP 11. Check whether the DTC is reset.
1. Erase the DTC.
2. Drive the vehicle at 12 mph (20 km/h) or higher.
  NOTE: The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12 mph (20 km/h) or higher.
Q: Is DTC C1073 set?
1. YES: Return to Step 1.
2. NO: The procedure is complete.